1. Technical Field
The invention relates to a male and female thread combination on a capping mechanism and a valve such as a pressure relief valve as used on life rafts, escape slides, white water rafts, kayaks, etc. where the male and female threads assure alignment of the cap on the valve when fully tightened down. More particularly, the invention relates to a self aligning male and female thread combination where the capping mechanism when threaded upon the valve such as a pressure relief valve always aligns before the cap is completely threadably tightened irregardless of whether the cap was properly aligned when the threading process began. Specifically, the invention is a valve such as a pressure relief valve and cap where slightly angled annular ridges, which are located between each of the exhaust ports in the valve in a spiral or thread-like manner, interact with an internal thread in the cap so as to align a misaligned cap by continuing to tighten the cap on the annular ridges.
2. Background Information
For years, valves such as pressure relief valves have been used in conjunction with various types of inflatable devices including life rafts, escape slides, etc. Other valves include inlet check valves, topping or inflate/deflate valves, and transfer valves. Generally, each of these valve types involves a valve body with only a few access ports. One access port fluidly connects the valve to within the inflatable device and is thus not subject to leakage. However, at least one port fluidly connects the valve to the environment, the area outside of the inflation device and thus its seal is critical to preventing leakage. As a result, it may be important in certain circumstances that it is protected from damage, debris blockage, etc.
Although damage in a few cases can be an issue, temporary internal pressure spikes are the main concern as to raft deflation and thus the main reason capping would be desirable. Such spikes are often a result of waves encountering the flexible raft and momentarily compressing the air therein resulting in a pressure spike that may open the pressure relief valve thereby incrementally deflating the raft. As waves are continuous, this intermittent process may eventually deflate the raft. This is accentuated in rough seas.
One example where it has been found that such incremental pressure spiking and pressure relieving is very frequent is the area of inflatable assault boats. These inflatable assault boats must be rapidly inflated, thereafter remain inflated, and must be capable of high speed boating. It has been found that during such high speed boating, the waves and rough seas provide sufficient forces against the raft causing momentary pressure increases or spikes resulting from the turbulent and powerful waves and rough seas whereby the raft eventually deflates at least partially. The intermittent forcing open of the valves due to water pressure from the powerful waves is thus undesirable as deflation occurs. For these reasons, it would be highly desirable that after inflation of an assault boat, the pressure relief valves are capped.
Obviously, in the case of life rafts, waves also present similar problems although often not quite as grave due to the lack of high speed movement of life rafts versus assault boats. However, rough seas will often simulate the high speed conditions.
Another problem that may be encountered is the entry of debris into the valve. It is possible that such debris can become lodged in the valve and particularly at the poppet or other seal seat. As a result of debris across the seal, sealing may not occur resulting in slow leakage.
Finally, in very rare instances, a valve may not fully seal and as such capping would eliminate the concern surrounding such rare leaks.
It is critical that leaks be eliminated because even a slow leak over time may result in significant deflation of the inflatable device. Such deflation may be hazardous, particularly in the case of a life raft.
It is thus desirous to cap the entire valve assembly or at least the portion containing any access ports such that high seas and rough waves cannot temporarily spike the pressure within the inflatable device thereby forcing the valve open; this is accomplished by the present invention which caps the valve and holds the poppet closed. It is also desirous to prohibit debris from coming into contact with the valve (as damage or seal interference may result, either of which can cause leaking). This capping is not always an easy process as the valve may be in a peculiar, difficult to reach and/or see place. In addition, the inflation device may not be still during capping such as where a life raft is on the open, and possibly rough, sea. As a result, often the cap is either impossible to install, or very difficult to install. One such problem often encountered is that the threading of the cap is started but in a crooked, misaligned or cross-threaded manner. This requires removal of the cap followed by re-starting of the threading process which as stated above may be a difficult process due to the placement of the valve, and/or the rough seas.
Clearly, an improved capping mechanism is desirous. In addition to the desire to cap a leaky valve such as a pressure relief valve, it is sometimes necessary to disable the relief or other mechanisms of certain valves during certain operations, such as testing, involving the inflatable device. For example, leak testing and periodic service procedures on inflatable devices such as life rafts require either the disablement or removal and plugging of all pressure relief valves present in the inflation device because the raft must be over pressured. In the past, the pressure relief valve has been removed and a plug inserted in its place. Clearly, an easy-to-use cap for capping the pressure relief valve or other valve would be desirable where such capping would either or both cover the internal components of the valve and any exhaust ports, and/or force the valve into a closed seating position, that is depress the poppet or similar sealing mechanism.